1. Field of the Invention
The present invention relates to controlling the movement of a vehicle travelling along a roadway, more specifically to a method for applying stripes and lane markers to road surfaces.
2. Discussion of the Prior Art
Lane marking or striping of road surfaces is conventionally done by dispatching a survey party onto a roadway to place small marks or "cat-tracks" on the roadway. At some later time, another crew returns to paint strips or lane markers using the cat-tracks as a guide.
The vehicles that paint the lanes are frequently equipped with a mechanical boom or pointer device extending from the front of the vehicle to help the driver guide the vehicle along the cat-tracks. The boom is difficult to align along the cat tracks, as the distance between boom and driver is significant. A boom also poses a safety hazard since it extends much further forward than a normal vehicle. For example, upon arrival at an intersection, the boom protrudes into the intersection; this scenario has been the cause of many auto accidents. Further, use of the boom does not always make it possible to guide the vehicle, e.g. at intersections and hilltops.
Survey crews are ordinarily scheduled to maximize their efficiency, thus it may be a long period of time before lane markers are painted by the second crew. This can result in unmarked or ambiguous lane markings, thus increasing the potential for unsafe vehicle operation on the roadway.
The use of low power lasers to provide highly focused, visible red light is well known. Such laser beams are directional and controllable and their brilliance makes them ideal for visual optimizing. For instance, when a laser device is used to generate and cast a visible line of light along or across a log, a board, or plywood, the light is narrow and of even brightness for the entire line length. Such a line enables the sawyer to make a more accurate cut than is possible with traditional, incandescent, shadow-line based sawing equipment.
Laser beams have also been used as control systems for earthworking machines, as disclosed in Teach, U.S. Pat. No. 3,953,145. In Teach, a laser beam is periodically swept across the working area, and used in coordination with a mechanical tape machine to maintain the earthworker at a desired grade or elevation.